 /*******************************************************************************
  * Copyright (c) 2000, 2004 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Common Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/cpl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.ui.internal.commands;

 import java.util.ArrayList ;
 import java.util.Collections ;
 import java.util.List ;

 abstract class AbstractCommandRegistry implements ICommandRegistry {

     protected List activeKeyConfigurationDefinitions = Collections.EMPTY_LIST;
     protected List categoryDefinitions = Collections.EMPTY_LIST;
     protected List commandDefinitions = Collections.EMPTY_LIST;

     private CommandRegistryEvent commandRegistryEvent;
     private List commandRegistryListeners;
     protected List handlers = Collections.EMPTY_LIST;
     protected List imageBindingDefinitions = Collections.EMPTY_LIST;
     protected List keyConfigurationDefinitions = Collections.EMPTY_LIST;
     protected List keySequenceBindingDefinitions = Collections.EMPTY_LIST;

     protected AbstractCommandRegistry() {
         // Do nothing
 }

     public void addCommandRegistryListener(ICommandRegistryListener commandRegistryListener) {
         if (commandRegistryListener == null)
             throw new NullPointerException ();

         if (commandRegistryListeners == null)
             commandRegistryListeners = new ArrayList ();

         if (!commandRegistryListeners.contains(commandRegistryListener))
             commandRegistryListeners.add(commandRegistryListener);
     }

     protected void fireCommandRegistryChanged() {
         if (commandRegistryListeners != null) {
             for (int i = 0; i < commandRegistryListeners.size(); i++) {
                 if (commandRegistryEvent == null)
                     commandRegistryEvent = new CommandRegistryEvent(this);

                 (
                     (ICommandRegistryListener) commandRegistryListeners.get(
                         i)).commandRegistryChanged(
                     commandRegistryEvent);
             }
         }
     }

     public List getActiveKeyConfigurationDefinitions() {
         return activeKeyConfigurationDefinitions;
     }

     public List getCategoryDefinitions() {
         return categoryDefinitions;
     }

     public List getCommandDefinitions() {
         return commandDefinitions;
     }

     /**
      * An accessor for the handlers read into this registry.
      *
      * @return The list of handlers; this value may be empty, but it is never
      * <code>null</code>.
      */
     public List getHandlers() {
         return handlers;
     }

     public List getImageBindingDefinitions() {
         return imageBindingDefinitions;
     }

     public List getKeyConfigurationDefinitions() {
         return keyConfigurationDefinitions;
     }

     public List getKeySequenceBindingDefinitions() {
         return keySequenceBindingDefinitions;
     }

     public void removeCommandRegistryListener(ICommandRegistryListener commandRegistryListener) {
         if (commandRegistryListener == null)
             throw new NullPointerException ();

         if (commandRegistryListeners != null)
             commandRegistryListeners.remove(commandRegistryListener);
     }
 }

